Charlie Day: I wouldn't want to do 'It's Always Sunny in Philadelphia' without Dennis Reynolds

Day also has a message to Philly fans upset over his TV ad with Cowboys' Dak Prescott

An "It's Always Sunny in Philadelphia" without Dennis? Charlie Day can't see it.

The actor who plays Charlie Kelly on the FXX series opened up on what the series would look like without Glenn Howerton, who plays Dennis Reynolds. Howerton's return to the show isn't clear, especially after NBC picked up a pilot he and Patton Oswalt star in called "A.P. Bio," spearheaded by Seth Meyers and Lorne Michaels, back in May.

“We really never want to do the show without Dennis," he told the publication. "There is a possibility that maybe we would have Dennis in part of a season, not a complete season. I think we would still do a great season. There is a possibility that we have Dennis for an entire season, which would be fantastic.”

The actor's also teamed up for a series of DirecTV's Sunday Ticket ads, and one stars Day alongside the Dallas Cowboys' Dak Prescott. He didn't have the kindest words for Philadelphia fans who might be a bit offended.

"I apologize to anyone who’s under the delusion that I actually am my character from 'It’s Always Sunny in Philadelphia,'" he told the Huffington Post. "For anything I happen to do in my life that does not directly correlate with the behavior of that character that displeases the fans, I truly apologize; however, for anyone who is that delusional, I think, get over it."

Upset? They say time heals all wounds. While the 12th season of "It's Always Sunny in Philadelphia" aired in early March, fans of the gang will have to wait unusually long for the show's return. Season 13 isn't likely to come back until late 2018 or early 2019, according to Uproxx.